It is common to use a contact block having either a normally closed or a normally open contact to control the current flowing in an electrical circuit. The contact block can typically be used in a limit switch, with a push button operator to form a push button switch, or in any other situation wherein an object can physically move an actuator thereby causing the normally closed or normally open contacts to change state. The contact block generally comprises a first pair of stationary contacts and a pair of movable contacts attached to the actuator. The actuator is biased such that the movable contacts are either in the closed or open position with relation to the first stationary contacts. It is also known to have a second pair of stationary contacts spaced apart from the first pair of stationary contacts such that the pair of movable contacts are located between the first and second stationary contacts, thus allowing the contact block to have one normally open contact and one normally closed contact. The extra set of stationary contacts increases the physical size of the contact block and significantly increases the cost since two additional stationary contacts, two wiring terminals and the bussing connecting the contacts to the terminals are required. If an application requires two contacts of the same type it is common to "stack", contact blocks together This is accomplished by attached one contact block to another, such that each subsequent contact block is operated by the actuator of the contact block to which it is attached. Since the options described above each add additional cost to the contact block, it would be desirable to have a contact block which is comparable in size and cost to a single function contact block of the prior art and yet is easily converted from a normally open to a normally closed contact block. It is also desirable to have a contact block which is easily converted from a normally open normally closed combination to either two normally closed or two normally open contacts.
In other types of circuit control devices employing a stationary contact and a movable contact operated by an actuator to make or break the circuit it is sometimes required that an additional control circuit be operated by the same actuator. For these applications it is common to provide an auxiliary contact. The auxiliary contact is generally contained within an enclosure and includes a pair of stationary contacts, a pair of movable contacts mounted on an actuator, a biasing spring, and a pair of wire terminal connectors. The auxiliary contact enclosure is mounted on the outside of the circuit control device enclosure in a location that permits access to the primary contactor actuator such that the auxiliary contact can be operated simultaneously with the primary contactor. Therefore, the trip mechanism of the primary contactor must be designed to overcome not only the biasing spring and latching friction of the primary contacts but also the biasing spring of the auxiliary contact. This increases the cost of the circuit control device regardless of whether or not an auxiliary contact is employed. The auxiliary contacts, like the contact blocks, are available in either a normally open or a normally closed function and must be purchased separately as an accessory for the control device. This means that an inventory of both normally open and normally closed auxiliary contacts is required to insure that the desired auxiliary contact is available when required. It would therefore be desirable to have a circuit control device with an internal auxiliary contact that can be easily converted from a normally open to a normally closed contact and which does not have an additional biasing spring for the trip mechanism to overcome.